U.S. patent number 10,401,555 [Application Number 15/596,007] was granted by the patent office on 2019-09-03 for light guide plate, display device and game machine.
This patent grant is currently assigned to OMRON Corporation. The grantee listed for this patent is OMRON Corporation. Invention is credited to Junya Fujita, Yoshimasa Osumi, Yoshihiko Takagi.
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United States Patent |
10,401,555 |
Fujita , et al. |
September 3, 2019 |
Light guide plate, display device and game machine
Abstract
A light guide plate according to one or more embodiment is
formed of a panel transparent to visible light, and includes: a
plurality of first prisms arranged along one surface of the light
guide plate and distributed in a first pattern to reflect the
visible light emitted from a first light source and entering the
light guide from an input surface toward another surface of the
light guide plate; and a plurality of second prisms arranged in a
second pattern to reflect the visible light emitted from a second
light source and entering the light guide from the input surface
toward said other surface of the light guide plate. Each first
prism includes a reflection surface directly facing the first light
source, and each second prism includes a reflection surface
directly facing the second light source.
Inventors: |
Fujita; Junya (Ichinomiya,
JP), Osumi; Yoshimasa (Kyoto, JP), Takagi;
Yoshihiko (Kyoto, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
OMRON Corporation |
Kyoto-shi, Kyoto |
N/A |
JP |
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Assignee: |
OMRON Corporation (Kyoto-shi,
JP)
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Family
ID: |
56149954 |
Appl.
No.: |
15/596,007 |
Filed: |
May 16, 2017 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20170248749 A1 |
Aug 31, 2017 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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PCT/JP2015/080941 |
Nov 2, 2015 |
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Foreign Application Priority Data
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Dec 25, 2014 [JP] |
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2014-263591 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G09F
13/005 (20130101); G02B 6/00 (20130101); G02B
6/0068 (20130101); G02B 6/006 (20130101); G02B
6/0036 (20130101); A63F 7/02 (20130101) |
Current International
Class: |
A63F
7/02 (20060101); G09F 13/00 (20060101); G02B
6/00 (20060101); F21V 8/00 (20060101) |
Field of
Search: |
;463/31 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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S58-123580 |
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Jul 1983 |
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JP |
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H11-231797 |
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Aug 1999 |
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JP |
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2003-519810 |
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Jun 2003 |
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JP |
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2003-249111 |
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Sep 2003 |
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JP |
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2005-142128 |
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Jun 2005 |
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JP |
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2005-353544 |
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Dec 2005 |
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JP |
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2006-310269 |
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Nov 2006 |
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JP |
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2011-247993 |
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Dec 2011 |
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JP |
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2012-118378 |
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Jun 2012 |
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JP |
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2013-000299 |
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Jan 2013 |
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JP |
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Other References
Japanese Office Action dated May 8, 2018 in a counterpart Japanese
patent application. cited by applicant .
German Office Action dated Jan. 8, 2019 in a counterpart German
patent application. cited by applicant.
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Primary Examiner: Elisca; Pierre E
Attorney, Agent or Firm: Metrolex IP Law Group, PLLC
Parent Case Text
This application is a continuation application of International
Application No. PCT/JP2015/080941, filed on Nov. 2, 2015, which
claims priority based on the Article 8 of Patent Cooperation Treaty
from prior Japanese Patent Applications No. 2014-263591, filed on
Dec. 25, 2014, the entire contents of which are incorporated herein
by reference.
Claims
The invention claimed is:
1. A light guide plate formed of a panel transparent to visible
light, the light guide plate comprising: an input surface
configured to form a sidewall of the light guide plate that faces a
first light source and a second light source aligned along the
sidewall, the first light source and the second light source
configured to emit visible light; a plurality of first prisms
arranged along one surface of the light guide plate and distributed
in a first pattern to reflect the visible light emitted from the
first light source, the visible light entering the light guide
plate from the input surface toward an other surface of the light
guide plate; and a plurality of second prisms arranged along the
one surface of the light guide plate and distributed in a second
pattern different from the first pattern to reflect the visible
light emitted from the second light source and entering the light
guide plate from the input surface toward the other surface of the
light guide plate, wherein each first prism in the plurality of
first prisms comprises a reflection surface directly facing the
first light source, and each second prism in the plurality of
second prisms comprises a reflection surface directly facing the
second light source.
2. The light guide plate according to claim 1, wherein a density of
the plurality of first prisms increases as a distance from the
first light source increases, and a density of the plurality of
second prisms increases a distance from the second light source
increases.
3. The light guide plate according to claim 1, wherein each first
prism in the plurality of first prisms is formed so that an end
portion of the first prism in the plurality of first prisms closer
to the second light source is narrower in a direction orthogonal to
the reflection surface of the first prism in the plurality of first
prisms, than a width of the first prism in the plurality of first
prisms in the direction orthogonal to the reflection surface at a
center of the reflection surface of the first prism in the
plurality of first prisms.
4. The light guide plate according to claim 1, wherein the first
light source comprises two light emitting elements arranged along a
length direction of the input surface with a predetermined gap
therebetween; and each first prism in the plurality of first prisms
is arranged so that the reflection surface of each first prism in
the plurality of first prisms directly faces between the two light
emitting elements.
5. The light guide plate according to claim 1, wherein the first
light source comprises a plurality of light emitting elements
arranged along a length direction of the input surface with a
predetermined gap therebetween; and each first prism in the
plurality of first prisms is arranged so that the reflection
surface of each first prism in the plurality of first prisms
directly faces a light emitting element in the plurality of light
emitting elements.
6. The light guide plate according to claim 5, wherein each first
prism in the plurality of first prisms are arranged so that the
reflection surface of each first prism in the plurality of first
prisms directly faces the light emitting element in the plurality
of light emitting elements that provides a maximum illumination at
a location of the first prism.
7. A display device comprising: a first light source configured to
emit visible light; a second light source aligned with the first
light source and configured to emit visible light; a light guide
plate formed from a panel transparent to visible light; and a
processor configured to perform operations comprising operation as
a controller configured to control a turning on and off of the
first light source and the second light source; the light guide
plate comprising: an input surface configured to form one sidewall
of the light guide plate facing the first light source and the
second light source; a plurality of first prisms arranged along one
surface of the light guide plate and distributed in a first pattern
to reflect the visible light emitted from the first light source
that enters the light guide plate from the input surface toward an
other surface of the light guide plate; and a plurality of second
prisms arranged along the one surface of the light guide plate and
distributed in a second pattern different from the first pattern to
reflect the visible light emitted from the second light source that
enters the light guide plate from the input surface toward the
other surface of the light guide plate, wherein each first prism in
the plurality of first prisms comprises a reflection surface
directly facing the first light source, and each second prism in
the plurality of second prisms comprises a reflection surface
directly facing the second light source.
8. A game machine comprising: a playfield; and a display device
provided on a surface of the playfield facing a player; the display
device comprising: a first light source configured to emit visible
light; a second light source aligned with the first light source
and configured to emit visible light; a light guide plate formed
from a panel transparent to visible light; and a processor
configured to perform operations comprising operation as a
controller configured to control a turning on and off of the first
light source and the second light source; the light guide plate
comprising: an input surface configured to form one sidewall of the
light guide plate facing the first light source and the second
light source; a plurality of first prisms arranged along one
surface of the light guide plate and distributed in a first pattern
to reflect the visible light emitted from the first light source
that enters the light guide plate from the input surface toward an
other surface of the light guide plate provided facing the player;
and a plurality of second prisms arranged along the one surface of
the light guide plate and distributed in a second pattern different
from the first pattern to reflect the visible light emitted from
the second light source that enters the light guide plate from the
input surface toward the other surface of the light guide plate,
wherein each first prism in the plurality of first prisms comprises
a reflection surface directly facing the first light source, and
each second prism in the plurality of second prisms comprises a
reflection surface directly facing the second light source.
Description
FIELD
The present disclosure relates to a light guide plate that allows
switching of a pattern displayed. The present invention also
relates to a display device, and a game machine having such kind of
display device.
BACKGROUND
Luminaires, i.e., illumination devices have been proposed which
include a panel-like light guide plate made from optically
transmissive material. The illumination devices proposed causes a
pattern to be shown in accordance with the direction light enters
the light guide plate (for instance, Japanese Unexamined Patent
Publication Number 2003-519810).
The illumination device disclosed in JP 2003-519810 A includes an
optically transmissive panel. The panel is arranged between a light
output window, and a rear wall facing the light output window, and
includes optically transmissive first and second end surfaces that
are arranged at mutually different locations. Light entering the
panel from a light source facing the first end surface is reflected
by the plurality of rectangular prisms aligned along a first light
symbol formed on the rear wall. The light then exits from a light
output surface causing a first light symbol to be shown. In
contrast, light entering the panel from a light source facing the
second end surface is reflected by the plurality of rectangular
prisms aligned along a second light symbol formed on the rear wall.
The light then exits from the light output surface causing a second
light symbol to be shown.
[Patent Document 1] Japanese Unexamined Publication No.
2003-519810
SUMMARY
As above described, the illumination device disclosed in JP
2003-519810 includes a plurality of light sources arranged to face
two mutually different sides of the panel. However, depending on
how the display device will be used, it may be impossible to
arrange the light sources along more than one end of the light
guide in the display device.
Therefore, to address this inflexibility, embodiments of the
present invention provide a light guide plate that allows switching
of the pattern displayed in accordance with the activation of a
portion of the plurality of light sources, even when the plurality
of light sources can only be arranged along one end of the light
guide plate.
One embodiment of the present invention provides for a light guide
plate formed from a panel transparent to visible light. The light
guide plate includes an input surface configured to form the
sidewall of the light guide plate that faces a first light source
and a second light source aligned therealong, the first light
source and the second light source configured to emit visible
light; a plurality of first prisms arranged along one surface of
the light guide plate and distributed in a first pattern to reflect
the visible light emitted from a first light source and entering
the light guide from an input surface toward another surface of the
light guide plate; a plurality of second prisms arranged in a
second pattern to reflect the visible light emitted from a second
light source and entering the light guide from the input surface
toward said other surface of the light guide plate.
Each first prism in the plurality of first prisms includes a
reflection surface directly facing the first light source, and each
second prism in the plurality of second prisms includes a
reflection surface directly facing the second light source.
The light guide plate may be configured so that the density of the
plurality of first prisms increases as the distance from the first
light source increases, and the density of the second prisms
increases as the distance from the second light source
increases.
The light guide plate may also be configured such that each of the
first prisms in the plurality of first prisms is formed so that the
end portion of the first prism closer to the second light source is
narrower in the direction orthogonal to the reflection surface of
the first prism than the width in the direction orthogonal to the
reflection surface at the center of the reflection surface of the
prism.
The first light source may include two light emitting elements
arranged along the length direction of the input surface with a
predetermined gap therebetween; and each of the first prisms may be
arranged in the light guide plate so that the reflection surface
thereof directly faces between the two light emitting elements.
The first light source may include a plurality of light emitting
elements arranged along the length direction of the input surface
with a predetermined gap therebetween; and each of the first prisms
may be arranged in the light guide plate so that the reflection
surface thereof directly faces any one in the plurality of light
emitting elements.
In this case, each of the first prisms may be arranged so that the
reflection surface thereof directly faces the light emitting
element that provides the maximum illumination at the location of
that first prism.
Another embodiment of the present invention provides a display
device. The display device includes a first light source configured
to emit visible light; a second light source aligned with the first
light source and configured to emit visible light; a light guide
plate formed from a panel transparent to visible light; and a
controller configured to control turning on and off the first light
source and the second light source.
The light guide plate includes an input surface configured to form
one sidewall of the light guide plate facing a first light source
and a second light source; a plurality of first prisms arranged
along one surface of the light guide plate and distributed in a
first pattern to reflect the visible light emitted from a first
light source and entering the light guide from an input surface
toward another surface of the light guide plate; a plurality of
second prisms arranged in a second pattern to reflect the visible
light emitted from a second light source and entering the light
guide from the input surface toward said other surface of the light
guide plate. Each first prism in the plurality of first prisms
includes a reflection surface directly facing the first light
source, and each second prism in the plurality of second prisms
includes a reflection surface directly facing the second light
source.
Another embodiment of the present invention provides a game
machine. The game machine includes a main game unit; and a display
device provided on the surface of the main game unit facing a
player. The display device includes a first light source configured
to emit visible light; a second light source aligned with the first
light source and configured to emit visible light; a light guide
plate formed from a panel transparent to visible light; and a
controller configured to control turning on and off the first light
source and the second light source.
The light guide plate includes an input surface configured to form
one sidewall of the light guide plate facing a first light source
and a second light source; a plurality of first prisms arranged
along one surface of the light guide plate and distributed in a
first pattern to reflect the visible light emitted from a first
light source and entering the light guide from an input surface
toward another surface of the light guide plate provided facing a
player; a plurality of second prisms arranged in a second pattern
to reflect the visible light emitted from a second light source and
entering the light guide from the input surface toward said other
surface of the light guide plate. Each first prism in the plurality
of first prisms includes a reflection surface directly facing the
first light source, and each second prism in the plurality of
second prisms includes a reflection surface directly facing the
second light source.
A light guide plate according to one or more embodiments of the
present invention may allow switching of the pattern displayed in
accordance with the activation of a portion of the plurality of
light sources, even when the plurality of light sources can only be
arranged along one end of the light guide plate.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view illustrating a configuration of a
display device according to an embodiment;
FIG. 2 is a schematic front view of a light guide plate in the
display device;
FIG. 3 is a schematic lateral cross-sectional view of the light
guide plate along the line A-A' in FIG. 2;
FIG. 4A is an enlarged plan view of a portion of a first pattern
representing the arrangement of the first prisms;
FIG. 4B is an enlarged plan view of a portion of a second pattern
representing the arrangement of the second prisms;
FIG. 4C is an enlarged plan view depicting an overlapping region
where the first pattern and the second pattern overlap and
represents the arrangement of each kind of prism therein;
FIG. 5A depicts one example of modifying the arrangement pattern
for the prisms;
FIG. 5B depicts another example of modifying the arrangement
pattern for the prisms;
FIG. 6A depicts an example of modifying the shape of the
prisms;
FIG. 6B depicts an example of modifying the shape of the
prisms;
FIG. 7A depicts another example of modifying the shape of the
prisms;
FIG. 7B depicts another example of modifying the shape of the
prisms;
FIG. 8 is a plan view depicting a possible modification to the
light guide plate;
FIG. 9 is a plan view depicting another possible modification to
the light guide plate; and
FIG. 10 is a schematic perspective view, i.e., a user view of
pinball game machine including a display device according to the
above embodiments or modification examples.
DETAILED DESCRIPTION
A display device according to embodiments of the present invention
is described below with reference to the drawings. The display
device includes a light guide plate formed from a panel that is
transparent in visible light; one surface of the light guide plate
faces the observer and is taken as the light output surface. One of
the sidewalls surrounding the output surface of the light guide
plate serves as the input surface with a plurality of light sources
aligned along and facing the input surface. A plurality of prisms
are created on the other surface of the light guide plate facing
the light output surface; the plurality of prisms reflect the
visible light emitted from the light source and entering the light
guide plate toward the light output surface. The plurality of
prisms is grouped to correspond to the plurality of light sources.
Each group of prisms is distributed to coincide with the pattern
shown by the display device. The groups of prisms are further
arranged so that the reflection surface of the prisms in the group
directly faces the light source to which the group corresponds.
In the description that follows, the side of the light guide panel
facing the observer is assumed to be the front surface, and the
opposite surface taken as the rear surface.
FIG. 1 is a schematic view illustrating a configuration of a
display device according to an embodiment of the present invention.
The display device 1 includes a light guide plate 2, a first light
source 3, a second light source 4, and a controller 5.
The light guide plate 2 is produced from a panel like material that
is transparent with respect to the visible light emitted from the
first light source 3 and the visible light emitted from the second
light source 4. For instance, the light guide plate 2 may be molded
from a visible-light-transparent resin of poly methyl methacrylate
(PMMA), a polycarbonate, or a cycloolefin polymer. The plurality of
first prisms is created on the rear surface of the light guide
plate 2 and distributed in a first pattern 22 that corresponds to
the first light source 3. When the first light sources are lit, the
first prisms propagate the light from the first light source 3
through the light guide plate 2 and toward the observer located in
front of the light guide plate; hereby the emission of first
pattern 22 is visible to the observer. The plurality of second
prisms is also created on the rear surface of the light guide plate
2 and is distributed in a second pattern 24 that corresponds to the
second light source 4. When the second light sources are lit, the
second prisms the light from the second light source 4 through the
light guide plate 2 and toward the observer located in front of the
light guide plate, thereby rendering the first pattern 22 exiting
the light guide plate visible to the observer. The specifics of the
light guide plate 2 are described later.
The first light source 3 and the second light source 4 each include
at least one light emitting element capable of emitting visible
light. The light emitting surface of the light emitting element is
arranged facing the input surface 2a, which is at least one of the
side walls in the light guide plate 2. The first light source and
the second light source are aligned along the input surface 2a and
disposed at mutually different locations. The controller 5 sends a
control signal according to which the first light source 3 or the
second light source 4 turns on or off. When the controller 5
illuminates the first light source 3, the light emitted from the
first light source 3 enters the light guide plate 2 via the input
surface 2a, travels through the light guide plate 2, is reflected
at the plurality of first prisms formed on the diffusion surfaces
2b at the rear surface of the light guide plate 2, and then exits
from the output surface 2c toward the front surface. In the same
manner, when the controller 5 illuminates the second light source
4, the light emitted from the second light source 4 enters the
light guide plate 2 via the input surface 2a, travels through the
light guide plate 2, is reflected at the plurality of second prisms
formed on the diffusion surfaces 2b at the rear surface of the
light guide plate 2, and then exits from the output surface 2c
toward the front surface.
Note that, the light emitting element in the first light source 3
and in the second light source 4 may be a light emitting diode, an
incandescent light, or a fluorescent light. The color emitted by
the first light source 3 and the color emitted by the second light
source 4 need not be identical and may be different from each
other. Finally, the brightness of the first light source 3 and the
brightness of the second light source 4 need not be identical and
may be different from each other.
The controller 5 may include a processor, a memory circuit, and a
drive circuit for each of the light sources. The controller 5 may
turn the first light source 3 and the second light source for on or
off in accordance with a control signal from a control device (not
shown) in a host computer. When rendering a first pattern visible
to an observer located in front of the light guide plate 2, the
controller 5 may turn on the first light source 3 and turn off the
second light source 4. Conversely, when rendering a second pattern
visible to an observer located in front of the light guide plate 2,
the controller 5 may turn off the first light source 3, and turn on
the second light source 4.
The specifics of the light guide plate 2 are described below.
FIG. 2 is a schematic front view of the light guide plate 2. FIG. 3
is a schematic lateral cross-sectional view of the light guide
plate along the line A-A' in FIG. 2. As illustrated in FIG. 2 and
FIG. 3, the input surface 2a is formed on one sidewall surface of
the light guide plate 2 facing the first light source 3 and the
second light source 4. Light from the first light source 3 enters
the light guide plate 2 from the input surface 2a. The light
propagating in the light guide plate 2 is totally reflected by the
plurality of first prisms 21 formed on the diffusion surface 2b
located on the rear surface of the light guide plate 2. Thereafter,
this light is output from the output surface 2c that is located on
the front surface of the light guide plate 2 and is facing the
diffusion surface 2b. The plurality of first prisms 21 is
distributed along a first pattern 22 to create the first pattern
22. Consequently, while the first light source 3 is illuminated an
observer will be able to see the light emitted from the first
pattern 22 on the surface of the light guide plate 2. The sizes of
the first prisms 21 and the second prisms 22, and the thickness of
the light guide plate 2 are exaggerated in FIG. 2 and FIG. 3 for
illustrative purposes.
Similarly, light from the second light source 4 enters the light
guide plate 2 from the input surface 2a. The light propagating in
the light guide plate 2 is totally reflected by the plurality of
second prisms 23 formed on the diffusion surface 2b and exits from
the output surface 2c. The plurality of second prisms 23 is
distributed along a second pattern 24 to create the second pattern
24. Consequently, while the second light source 4 is illuminated an
observer will be able to see the light emitted from the second
pattern 24 on the surface of the light guide plate 2.
Each of the first prisms 21 may be formed in the diffusion surface
2b, for example, as a roughly triangular groove of a predetermined
length. Each of the first prisms 21 has a reflection surface 21a
that forms a predetermined angle with the diffusion surface 2b.
Similarly, each of the second prisms 23 may be formed in the
diffusion surface 2b, for example, as a roughly triangular groove
of a desired length. Each of the second prisms 23 has a reflection
surface 23a that forms a predetermined angle with the diffusion
surface 2b. This predetermined angle is established so that light
from the first light source 3 or the second light source 4 entering
the light guide plate 2 is totally internally reflected and travels
toward the output surface 2c; this angle may be 40.degree. to
60.degree. relative to the diffusion surface 2b. The predetermined
length is long enough to allow the plurality of prisms to be
distributed within the first pattern 22 and the second pattern 24;
for instance, this predetermined length may be 100 .mu.m to several
millimeters.
FIG. 4A is an enlarged plan view of a portion of the first pattern
22 representing the arrangement of the first prisms 21. The
plurality of first prisms 21 is staggered inside the first pattern
22. That is, within the first pattern 22, the plurality of first
prisms 21 are disposed at equal intervals along a direction
parallel to the input surface 2a of the light guide plate 2 (for
brevity, referred to as the x direction), and disposed at a
predetermined pitch along a line orthogonal to the input surface 2a
(for brevity, referred to as the y direction). Further the position
of two first prisms 21 next to each other in adjacent rows are
offset in the y direction. Rows of first prisms are positioned so
that two adjacent first prisms 21 are offset by half the pitch.
Each of the first prisms 21 is arranged so that the reflection
surface 21a thereof directly faces the first light source 3 in a
plane parallel to the diffusion surface 2b. That is, in the
embodiment, the reflection surface 21a of a first prism 21
positioned a predetermined distance away from the first light
source 3 is centered about the first light source 3 and oriented
substantially parallel to a circle whose radius is said
predetermined distance.
Therefore, arranging the plurality of first prisms 21 in this
manner allows each of the first prisms 21 to reflect light from the
first light source 3 entering via the input surface 2a roughly
perpendicular to the output surface 2c. In contrast, light other
than light from first light source 3 entering the input surface 2a,
e.g., light from the second light source 4 or stray light, forms a
relatively large angle with the output surface 2c and exits
therefrom. Therefore, this light is hardly visible to an observer
in front of the light guide plate 2, even if the light were
reflected from the first prisms 21. As a result, the display device
1 is able to present an observer with the first pattern 22 only
while the first light source 3 is turned on.
FIG. 4B is an enlarged plan view of a portion of the second pattern
24 representing the arrangement of the second prisms 23. Similar to
the first prisms 21, the plurality of second prisms 23 is staggered
inside the second pattern 23. Each of the second prisms 23 are
arranged so that the reflection surface 23a thereof directly faces
the first light source 3 in a plane parallel to the diffusion
surface 2b. Therefore, in the embodiment, the reflection surface
23a of a second prism 23 positioned a predetermined distance away
from the second light source 4 is centered on the second light
source 4 and oriented as substantially parallel to a circle whose
radius is said predetermined distance.
Thusly arranging the plurality of second prisms 23 allows each of
the second prisms 23 to reflect light from the second light source
4 entering via the input surface 2a roughly perpendicular to the
output surface 2c. In contrast, light other than light from second
light source 4 entering the input surface 2a, e.g., light from the
first light source 3 or stray light, forms a relatively large angle
with the output surface 2c and exits therefrom. Therefore, this
light is hardly visible to an observer in front of the light guide
plate 2, even if the light were reflected from the second prisms
23. As a result, the display device 1 is able to present an
observer with the second pattern 24 only while the second light
source 4 is turned on.
FIG. 4C is an enlarged plan view depicting an overlapping region
where the first pattern 22 and the second pattern 24 overlap and
represents the arrangement of each kind of prism therein.
In the embodiment, the first prisms 21 forming the first pattern 22
and the second prisms 23 forming the second pattern 24 are all
staggered; therefore, the first prisms 21 and the second prisms 23
alternate in the area where the first pattern 22 and the second
pattern 24 overlap. As a result, a pattern can be displayed in
accordance with the light source that is illuminated even if the
first pattern 22 and the second pattern 24 overlap. This is because
on illuminating the first light source 3, the first prisms 21 guide
light from the first light source 3 toward the output surface 2c,
whereas on illuminating the second light source 4, the second
prisms 23 guide light from the second light source 4 toward the
output surface 2c. As above mentioned, the first prisms 21 and the
second prisms 23 are arranged in a particular way; this provides
flexibility for the first pattern 22, and the second pattern 24 to
be arranged in a desired shape, as well as improves the appearance
when the patterns and another region create a border that lies
along a straight line.
Note that the first prisms 21 and the second prisms 23 may be
arranged as lattices. Furthermore, the prisms may be distributed so
that a line in the y direction along which the first prisms 21 are
arranged alternates with a line in the y direction along which the
second prisms 23 are arranged within the region where the first
pattern 22 and the second pattern 24 overlaps.
As above described, a plurality of first and a plurality of second
prisms are arranged in the display device to create a first and
second pattern shown via the light guide plate. The plurality of
first prisms is arranged so that the reflection surfaces thereof
are directly facing the light source corresponding to the first
pattern, and the plurality of second prisms is arranged so that the
reflection surfaces thereof are directly facing the light source
corresponding to the second pattern. Hereby, the display device can
switch the pattern displayed by switching the light source that is
illuminated. This can be accomplished even when a plurality of
lights sources is arranged facing one side of the light guide
plate, since the prisms forming the pattern correspond to the light
illuminated, the prisms direct the light from the corresponding
light source out of the light guide plate.
As an example modification, the plurality of prisms forming the
individual patterns may be arranged with increasing density in
accordance with the distance from the light source to thereby
mitigate uneven luminance in the pattern.
FIG. 5A depicts one example of modifying the arrangement pattern
for the prisms. In this modification example, the plurality of
first prisms 21 forming the first pattern 22 are arranged at
increasing density in relation to the distance from the first light
source 3. The first prisms are also at equal intervals on a line
along the y direction. Similarly, the plurality of second prisms 23
forming the second pattern 24 are arranged at increasing density in
relation to the distance from the second light source 4, and
positioned at equal intervals on a line along the y direction.
Arranging the prisms in this manner increases the number of prisms
that reflect light from the light source toward the output surface
2c of the light guide plate 2 in accordance with the distance from
each of the light sources; therefore, the display device can
thereby mitigate any uneven luminance in the pattern. The density
of the first prisms 21 may be established so that a function
representing the relationship between the distance from the first
light source 3 and the density of the first prisms 21 is the
inverse of an intensity function representing the distance from and
the luminance of the first light source 3. Similarly, the density
of the second prisms 23 may be established so that a function
representing the relationship between the distance from the second
light source 4 and the density of the second prisms 23 is the
inverse of an intensity function representing the distance from and
the luminance of the second light source 4.
Furthermore, the prisms are distributed so that a line in the y
direction along which the first prisms 21 are arranged alternates
with a line in the y direction along which the second prisms 23 are
arranged within the region where the first pattern 22 and the
second pattern 24 overlaps. However, the positions of an adjacent
first prism 21 and second prism 23 may be mutually different so
that overall, the prisms are staggered. Because arranging the
prisms in this manner allows a margin in the intervals between
adjacent prisms, the line along which the first prisms 21 are
arranged may be a shorter distance from the line along which the
second prisms 23 are arranged, and thus allows for distributing the
prisms at a greater density.
FIG. 5B depicts another example of modifying the arrangement
pattern for the prisms. As with the modification example depicted
in FIG. 5A, in this modification example, the plurality of first
prisms 21 forming the first pattern 22 are arranged at increasing
density in relation to the distance from the first light source 3.
Additionally, the first prisms are positioned at equal intervals on
a line along the y direction. The second prisms 23 which form the
second pattern 24 are also arranged at increasing density in
relation to the distance from the second light source 4.
Additionally, the second prisms are positioned at equal intervals
on a line along the y direction. However, the prisms are
distributed so that a line in the y direction along which the first
prisms 21 are arranged alternates with a line in the y direction
along which the second prisms 23 are arranged within the region
where the first pattern 22 and the second pattern 24 overlaps.
Additionally, adjacent first prisms 21 and second prisms 23 are at
the same position in the respective y directions.
The first prisms 21 are arranged so that even between the plurality
of lines in the y direction along which the first prisms 21 are
arranged, the density of the first prisms 21 arranged on that line
increases as the distance from the first light source 3 increases.
The second prisms 23 are also arranged so that even between the
plurality of lines in the y direction along which the second prisms
23 are arranged, the density of the second prisms 23 arranged on
that line increases as the distance from the second light source 4
increases.
In another modification example, the closer the end portion of the
first prism 21 is to the second light source 4, the shorter that
end portion is in the direction orthogonal to the reflection
surface 21a (hereafter, the width, which narrows). The second
prisms 23 are configured similarly to the first prisms in that the
end portions of the second prisms 23 closer to the first light
source 3 are narrower in the direction orthogonal to the reflection
surface as the end portions approach the first light source 3.
FIG. 6A and FIG. 6B depict examples for modifying the shape of the
prisms.
The first prisms 21 and the second prisms 23 may have the same
shape; therefore, FIG. 6A and FIG. 6B only depict the first prism
21 as the example.
FIG. 6A is a view of a first prism 21 from the front surface of the
light guide plate 2, i.e., from the output surface 2c side of the
light guide plate 2; the first prism 21 is shaped like an ellipse
cut in half along its major axis. FIG. 6B illustrates the first
prism 21 viewed from near the first light source 3; the first prism
21 is shaped like an ellipse cut in half along its major axis.
FIG. 7A and FIG. 7B depict another example of modifying the shape
of the prisms. Since the first prisms 21 and the second prisms 23
may have the same shape, FIG. 7A and FIG. 7B only depict the first
prism 21 as the example. FIG. 7A is a view of a first prism 21 from
the output surface 2c side of the light guide plate 2; the first
prism 21 is a trapezoid with the reflection surface 21a forming the
base. FIG. 7B illustrates the first prism 21 viewed from near the
first light source 3; the first prism 21 is a trapezoid where the
side toward the diffusion surface 2b is the base.
In the examples depicted in FIGS. 6A and 6B, and in FIGS. 7A and
7B, the surface area of the first prism 21 is smaller when viewed
from its non-corresponding second light source 4. The smaller
surface area toward the second light source 4 therefore reduces the
amount of light that reaches the observer when the first prism 21
reflects light emitted from the second light source 4. The width of
the end portion of the first prism 21 further away from the second
light source 4 may be equal to the width of the first prism 21 at
the center of the reflection surface 21a. The end portion of the
first prism 21 further away from the second light source 4 may also
be wider than width of the first prism 21 at the center of the
reflection surface 21a and subsequently be made wider. This is so
that the first prism 21 itself shields the end portion away from
the second light source 4 from light emitted by the second light
source 4. The second prisms 23 may be structured similarly to the
first prisms 21. That is, the width of the end portion of the
second prism 23 further away from the first light source 3 may be
equal to the width of the second prism 23 at the center of the
reflection surface 23a; further, the width of the end portion of
the second prism 23 further away from the first light source 3 may
be wider than the width of the second prism 23 at the center of the
reflection surface 23a.
In yet another possible modification, the first light source 3
includes two light emitting elements. Here, the two light emitting
elements are arranged along the length direction of the input
surface 2a of the light guide plate 2 with a predetermined gap
therebetween. This predetermined gap may be a calculated by, for
example, multiplying the ratio of a distance I1 and a distance I2
by the space between the eyes of an average person; where, I1 is
the distance from the first light source 3 to the center of gravity
of the first pattern 22, and I2 is the distance from the light
guide plate 2 to a hypothetical observer. Hereby, this facilitates
light from one of the light emitting elements in the first light
source 3 reaching one of the observer's eyes, and light from the
other light emitting element in the first light source 3 reaching
the observer's other eye. Therefore, the observer is able to view
the first pattern 22 at both eyes. The second light source 4 may be
similarly configured to first light source; namely, the second
light source 4 may include two light emitting elements arranged
along the length direction of the input surface 2a of the light
guide plate 2 with a predetermined gap therebetween.
FIG. 8 is a plan view depicting a possible modification to the
light guide plate 2. Note that the second prisms 23 and the second
pattern 24 are not illustrated in FIG. 8 to simplify the drawing.
Additionally, only two of first prisms 21 are illustrated. Here,
the first prisms 21 are arranged so that the reflection surfaces
21a thereof directly face between the two light emitting elements
in the first light source 3. Hereby, when the observer views the
light guide plate 2 from the front of the light guide plate 2,
roughly the same amount of light is emitted from the light emitting
elements in the first light source 3 and reaches the left eye and
the right eye of the observer; this therefore makes the first
pattern more easily viewable through both eyes of the observer.
Here, the second prisms 23 are arranged in the same manner as the
first prisms 21. That is, the second prisms 23 are arranged so that
the reflection surfaces 23a thereof directly face between the two
light emitting elements in the second light source 4.
In yet another modification example, the first light source 3 may
include a plurality of light emitting elements arranged along the
length direction of the input surface 2a of the light guide plate 2
with a predetermined gap therebetween. Each of the first prisms 21
making up the first pattern 22 may be arranged so that the
reflection surface 21a is oriented toward any one in the plurality
of light emitting elements. In this case, the light emitting
element toward which a reflection surface 21a is oriented may be
randomly selected per prism. Hereby, compared to when the light
source 3 only includes a single light emitting element, multiple
light emitting elements provide a broader radiation direction for
the first pattern 22; therefore the observer has an even broader
range for viewing the first pattern 22. Similarly, the second light
source 4 may include a plurality of light emitting elements
arranged along the length direction of the input surface 2a of the
light guide plate 2 with a predetermined gap therebetween. Each of
the second prisms 23 making up the second pattern 24 may be
arranged so that the reflection surface 23a is oriented toward any
one in the plurality of light emitting elements.
FIG. 9 is a plan view depicting another possible modification to
the light guide plate. Note that the second prisms 23 and the
second pattern 24 are not illustrated in FIG. 9, to simplify the
drawing. Additionally, only two of the first prisms 21 are
illustrated. In this modification example, the first light source 3
may include a plurality of light emitting elements arranged along
the length direction of the input surface 2a of the light guide
plate 2 with a predetermined gap therebetween. Each of the first
prisms 21 making up the first pattern 22 may be arranged so that
the reflection surface 21a directly faces the light emitting
element that provides the maximum illumination at the location of
that first prism 21. For instance, the first light source 3
includes two light emitting elements 31, 32. The profile 901
depicted in FIG. 9 represents a directivity distribution of the
light emission intensity from the light emitting element 31; and
the profile 902 in the same drawing represents a directivity
distribution of the light emission intensity from the light
emitting element 32. As illustrated by the profiles 901, 902, the
intensity of light from the light emitting element 31 is greater
than the intensity of light from the light emitting element 32 at
the prism 21-1. Therefore, the present 21-1 is arranged to directly
face the light emitting element 31. Whereas, the intensity of light
from the light emitting element 32 is greater than the intensity of
light from the light emitting element 31 at the location of the
prism 21-2. Therefore, the present 21-2 is arranged to directly
face the light emitting element 32. Hereby, each of the first
prisms 21 reflects the light of the brightest light emitting
element in relation to the location of that first prism 21, and
orients that light towards the observer. Therefore, the display
device 1 can present a brighter display of the first pattern 22.
The second light source 4 is similarly configured. That is, the
second light source 4 may include a plurality of light emitting
elements arranged along the length direction of the input surface
2a of the light guide plate 2 with a predetermined gap
therebetween. Each of the second prisms 23 making up the second
pattern 24 may be arranged so that the reflection surface 23a
directly faces the light emitting element that provides the maximum
illumination at the location of that second prism 23.
In another possible modification, three or more light sources may
be aligned facing the input surface 2a. In this case, a plurality
of prisms may be formed on the diffusion surface 2b of the light
guide plate 2, with the reflection surface of a prism arranged to
directly face a particular light source, and the prisms distributed
along a predetermined pattern. In this manner, a light guide 2 and
a display device including the light guide 2 is capable of
switching the pattern displayed in accordance with the activation
of a light source.
In another possible modification, the distribution density or the
size of the prisms making up a pattern may be different for each
pattern. Thus, a light guide 2 and a display device including the
light guide 2 can provide a different brightness in accordance with
a pattern for display.
A display device according to any of the above embodiments or
modification examples may be mounted in a game machine such as
pinball machine or a slot machine. FIG. 10 is a schematic
perspective view, i.e., a user view of pinball game machine
including a display device according to the above embodiments or
modification examples. As illustrated in FIG. 10, a pinball machine
100 includes a playfield 101, which is the main game unit. The
playfield 101 is where play takes place and takes up a majority of
the machine, from the top portion to the center. The pinball
machine 100 also includes a ball trough 102 arranged below the
playfield 101, an operation portion 103 provided with a jog; a
liquid crystal display provided at roughly the center of the
playfield 101; and a display device 105 disposed on the front
surface of the liquid crystal display 104.
To aid in presentation of the game, the pinball machine 100
includes accessories 106 arranged on the front surface of the play
field 101, at the lower part thereof and surrounding the display
device 105. The playfield 101 includes rails 107 positioned at the
sides. The playfield 101 may also include multiple obstacle pins
(not shown) and at least one prize target 108.
The input unit 103 launches the pinball at a predetermined force
via a launcher (not shown) in accordance with the amount of
rotation of the jog by a player. A launched pinball travels upward
along the rails 107 and falls between the multiple obstacle pins.
When a sensor (not shown) detects that a pinball has entered any of
the prize targets 108, a main controller (not shown) provided on
the rear side of the playfield 101 pays out a predetermined number
of pinballs depending on the prize; the pinballs are paid out into
the ball trough 102 via a payout device (not shown). The main
controller also drives the liquid crystal display 104 and the
display device 105 via a CPU (not shown) provided on the rear side
of the playfield 101.
The display device 105 is merely one example of a display device
according to the above embodiments and modification examples; this
display device 105 may be attached to the playfield 101 so that the
output surface of the light guide plate is oriented toward the
player. Furthermore, in this example, the shape of the accessories
106 surrounding the display device 105 may limit the light sources
to being placed along one side at the top of the display device
105; therefore, the display device 105 can be installed so that the
light sources are located along the top. The controller in the
display device 105 may illuminate either of the first light source
or the second light source in accordance with a control signal from
the game CPU in response to the state of play. As a result, the
player may be presented with a video on the liquid crystal display
104 while viewing the first pattern corresponding to the first
light source or the second pattern corresponding to the second
light source. Alternatively, the controller may turn off both the
first light source and the second light source so that the observer
may view only the video presented on the liquid crystal display 104
via the light guide plate.
A person having ordinary skill in the art may make various
modifications in the above manner within the scope of the invention
in accordance with how the device will be used.
REFERENCE NUMERALS
1 Display device 2 Light guide plate 2a Input surface 2b Diffusion
surface 2c Output surface 3 First light source 31, 32 Light
emitting element 4 Second light source 21 First prism 21a
Reflection surface 22 First pattern 23 Second prism 23a Reflection
surface 24 Second pattern 5 Controller 100 Pinball machine 101
Playfield 102 Ball trough 103 Operation portion 104 Liquid crystal
display 105 Display device 106 Accessories 107 Rail 108 Prize
target
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